Sight-base for gun-barrels.



1&1649285 T. C. JOHNSON.

SIGHT BASE FOR GUN BARRELS.

APPLICATION FILED OCT-9. I914- Patented Dec. 14, 1915.

COLUMBIA PLANOGRAPH c0..wAsmNnToN. n. c.

unsrauatsnrs.

UNITED STATES PATENT OFFICE.

THOMAS C. JOHNSON, OF NEW HAVEN, CONNECTICUT, ASSIGNOR T WINCHESTER REPEATING ARMS C0,, OF NEW HAVEN, CONNECTICUT, A CORPORATION.

SIGHT-BASE FOR GUN-BARRELS.

Specification of Letters Patent.

Patented Dec. 14, 1915.

Application filed October 9, 1914. Serial No. 865,964.

To all whom it may concern Be it known that I, THOMAS C. JOHNSON, a citizen of the United States, residing at New Haven, in the county of New Haven and State of Connecticut, have invented a new and useful Improvement in Sight- Bases for Gun-Barrels; and I do hereby declare the following, when taken in connection with the accompanying drawings and the characters of reference marked thereon, to be a full, clear, and exact description of the same, and which said drawings constitute part of this application, and represent, m-

Figure 1 a broken plan view of a gunbarrel provided with my improved sightbase. Fig. 2 a view thereof in side elevation. Fig. 3 a view thereof in front elevation. Fig. 4 a broken view in side elevation of one of the modified forms which my invention may assume. Fig. 5 a front view thereof. Fig. 6 a broken view in side elevation of another modified form which my invention may assume. Fig. 7 a view thereof in front elevation. Fig. 8 a broken view in side elevation of another form of my invention. Fig. 9 a view thereof in "front elevation. Fig. 10 a broken View in side elevation of another modified form of my invention. Fig. 11 a view thereof in front elevation.

My invention relates to an improvement in sight-bases for gun-barrels, the object being to provide simple means for preventing injury to the bore of a gun-barrel at the time of applying a sight to its sight-base.

WVith this end in view, my invention consists in providing a sight-base with one or more displacement-spaces positioned to prevent any displacement or stretching of the metal of the base at the time of applying the sight, from being transmitted to the barrel and hence to the bore thereof, whereby the barrel is protected from any impairment of its integrity and consequently against loss of accuracy in firing.

My invention further consists in certain details-as will be hereinafter described and pointed out in the claim.

In carrying out my invention as shown in Figs. 1 to 3 inclusive, I locate a transverse displacement-space or opening 2 in the integral sight-base 3 formed upon the upper face of the gun-barrel 4 near the muzzle-end thereof, the said space 2 being situated directly below the transverse dovetail-slot 5 formed in the top of the sightbase for the reception of the dovetail-rib of the sight which is not shown, but which may be of any approved form. The said displacement-space 2 herein shown is formed by applying a circular milling tool to the opposite faces of the base 3 so as to make semi-circular cuts which intersect in the longitudinal center of the base and produce a transverse opening which flares on both sides. Now when the dovetail-rib of a sight is driven into the dovetail-slot 5 the floor 6 thereof is free to be stretched or displaced without transmitting any strain to or dislocating the adjacent portion of the wall of the bore of the gun. In other words, the space 2 by being interposed between the top of the base and the barrel, prevents that portion of the wall of the bore lying directly below the base 3 from being stretched, wrinkled, or otherwise distorted. Such distortions, although so slight as to be ordinarily inappreciable except by the shadow process of straightening gun-barrels, are very serious in their effect upon the accuracy of the arm and are entirely avoided by the production, as described, in the lower portion of the sight-base, of a displacementspace positioned to prevent the transmission to the barrel of upsetting strains of whatever nature or direction due to driving the rib of the sight into the slot of the sightbase.

In the modified construction shown by Figs. 4 and 5 of the drawings, the dovetail slot 7 of the sight-base 8 is isolated, as it were, from the barrel 9 by means of three transverse circular holes 10, together forming a displacement-space between the floor 11 of the slot 7 and the barrel.

In the construction shown by Figs. 5 and 7, the dovetail slot 12 is virtually isolated by a transverse displacement-space 13, from the barrel 14, the space 13 being out directly through the lower portion of the sight-base 15 and having straight forward and rear walls.

In the form shown by Figs. 8 and 9, the floor 16 of the dovetail-slot 17 in the sightbase 18 is separated from the gun-barrel 19 by means of two longitudinal slots 20 respectively located directly opposite each other in the lower portion of the sightbase.

In the construction shown by Figs. 10 and 11, the floor 21 of the dovetail slot 22 in the sight-base 23 is separated from the barrel 2% by two longitudinal displacement grooves 25 located opposite each other in the lower portion of the base and entering the forward edge thereof, but at their rear ends not cutting through the rear end thereof, as shown in Fig. 10.

It is apparent from the foregoing that in carying out my invention, I may resort to a variety of expedients for providing a displacement-space or spaces to prevent the transmittal of any of the strains of applying a gun-sight to the sight-base of a gun-barrel, to the barrel so as to impair the integrity of the bore thereof.

I claim A gun-barrel provided at its forward end with a sight-base having a transverse vertical slot and one or more displacementspaces positioned to prevent the transmittal to the bore of the barrel of any strains accompanying the application of an adjustable sight to the said transverse slot in the sight-base, whereby the Wall of the bore is prevented from being buckled at a point adjacent to the sight.

In testimony whereof, I have signed this specification in the presence of two subscribing witnesses.

THOMAS C. JOHNSON.

Witnesses G120. DUDLEY SEYMOUR,

C. L. \VEED.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

